Slip Yoke Assembly For Automotive Drive Train

Abstract

Automotive drive shafts having slip yoke assemblies that are designed and configured to transmit torque and allow for axial movement while also minimizing driveline vibrations. In some embodiments, the slip yoke assemblies may include one or more bearings that minimize angular misalignment and resist drive shaft bending forces. In some embodiments, the bearings may include a pair of precision mating diameters on a yoke shaft and splined sleeve. In yet other embodiments, the slip yoke assembly may include internal rod wipers to seal out environmental contaminants and retain lubricants.

What is claimed is: 
     
         1 . A slip yoke assembly for use in an automobile driveshaft comprising:
 an outer sleeve having an inner lumen and an internal spline located in a portion of said inner lumen;   a yoke shaft slidably disposed within said inner lumen and configured for movement over a working stroke between a fully-inserted position and a design-maximum-extended position, said yoke shaft having an external spline configured to engage said internal spline to form a splined joint; and   at least one bearing surface disposed between the outer sleeve and yoke shaft and spaced from the splined joint, said bearing surface configured and dimensioned to resist angular misalignment between said splined sleeve and said yoke shaft.   
     
     
         2 . A slip yoke assembly according to  claim 1 , wherein said yoke shaft has a proximal end and a distal end, said slip yoke assembly further comprising a flange yoke located at said proximal end, and wherein said at least one bearing surface comprises a proximal bearing located between said proximal end and said splined joint and a distal bearing located between said distal end and said splined joint. 
     
     
         3 . A slip yoke assembly according to  claim 2 , wherein:
 said proximal bearing has a first bearing surface area and said distal bearing has a second bearing surface area, and wherein said first bearing surface area is greater than said second bearing surface area.   
     
     
         4 . A slip yoke assembly according to  claim 2 , wherein
 said inner lumen of said splined sleeve includes a proximal internal locating diameter and a distal internal locating diameter; and   said yoke shaft includes a proximal outer locating diameter configured for operable engagement with said proximal internal locating diameter and a distal outer locating diameter configured for operable engagement with said proximal internal locating diameter;   wherein said proximal bearing comprises said proximal internal and external locating diameters and said distal bearing comprises said distal internal and external locating diameters.   
     
     
         5 . A slip yoke assembly according to  claim 4 , wherein said proximal outer locating diameter has a first outer diameter and said distal outer locating diameter has a second outer diameter and wherein the first outer diameter is greater than the second outer diameter. 
     
     
         6 . A slip yoke assembly according to  claim 5 , wherein said splined joint has a major diameter and a minor diameter, and wherein the first outer diameter is greater than the major diameter and the second outer diameter is less than the minor diameter. 
     
     
         7 . A slip yoke assembly according to  claim 4 , wherein:
 said proximal outer locating diameter has an outer diameter D2 and said distal outer locating diameter has an outer diameter D3; and   wherein, when said yoke shaft is positioned at the design-maximum-extended position, said proximal bearing has an axial contact length L2 and said distal bearing has an axial contact length L3;   wherein at least one of L3/D3 and L2/D2 is at least approximately 0.6.   
     
     
         8 . A slip yoke assembly according to  claim 2 , wherein:
 said proximal bearing has a proximal end and said distal bearing has a distal end;   said slip yoke assembly having a supported length extending between said proximal end of said proximal bearing to said distal end of said distal bearing;   wherein, during use, said supported length is constant.   
     
     
         9 . A slip yoke assembly according to  claim 8 , wherein:
 when said yoke shaft is positioned at the design-maximum-extended position, said slip yoke assembly has an unsupported length extending between an axis of rotation of said flange yoke and said proximal end of said proximal bearing; and   a ratio of said supported length to said unsupported length is greater than or equal to approximately 1.5.   
     
     
         10 . A slip yoke assembly according to  claim 9 , wherein said yoke shaft has a first outer diameter, and wherein a ratio of said supported length to said first outer diameter is greater than or equal to approximately 2.5. 
     
     
         11 . A slip yoke assembly according to  claim 1  in combination with an automobile drive train comprising an engine and transmission configured to deliver torque to a driveshaft, and a rear differential mounted on a suspension configured to receive torque from the driveshaft, the suspension permitting movement of the rear differential relative to the engine and transmission, wherein said driveshaft comprises said slip yoke assembly. 
     
     
         12 . An aftermarket slip yoke assembly for use in a replacement driveshaft for replacing an automobile original equipment driveshaft of an automobile drive train, the slip yoke assembly comprising:
 a splined sleeve having a proximal end;   a yoke shaft slidably disposed within said splined sleeve and forming a splined joint therebetween, said yoke shaft having an outer surface;   wherein said proximal end of said splined sleeve includes a rod wiper groove configured to house a rod wiper in direct contact with said yoke shaft outer surface to thereby prevent contaminants from entering said slip yoke assembly.   
     
     
         13 . An aftermarket slip yoke assembly according to  claim 12 , wherein said yoke shaft has a proximal end, said slip yoke assembly further comprising a flange yoke removeably coupled to said proximal end of said yoke shaft. 
     
     
         14 . An aftermarket slip yoke assembly according to  claim 13 , wherein said flange yoke has a distal face and wherein at least one of said distal face and said proximal end of said yoke shaft have precision locating features configured to facilitate precisely locating said flange yoke on said proximal end of said yoke shaft. 
     
     
         15 . An aftermarket slip yoke assembly according to  claim 12 , wherein said slip yoke assembly further comprises a drive shaft tube configured to couple said slip yoke assembly to other automobile drive train components, said driveshaft tube having an inner diameter;
 said splined sleeve having an inner wall and an outer wall, said inner wall including an internal spline and said outer wall including an outer locating diameter;   wherein said inner diameter of said driveshaft tube is sized and configured for sliding engagement with said outer locating diameter and said outer locating diameter is adjacent said internal spline.   
     
     
         16 . An aftermarket slip yoke assembly according to  claim 12 , wherein said slip yoke assembly further comprises at least one bearing designed and configured to prevent angular misalignment between said splined sleeve and said yoke shaft. 
     
     
         17 . An aftermarket slip yoke assembly according to  claim 16 , wherein said splined sleeve has an inner wall, and wherein said bearing comprises said inner wall and said outer surface of said yoke shaft. 
     
     
         18 . A slip yoke assembly according to  claim 17 , wherein said outer surface is in direct contact with said inner wall. 
     
     
         19 . A slip yoke assembly according to  claim 17 , wherein said slip yoke assembly further comprises a bushing disposed between said outer surface of said yoke shaft and said inner wall of said splined sleeve. 
     
     
         20 . A slip yoke assembly according to  claim 16 , wherein a ratio of a length of said bearing to an outer diameter of said yoke shaft is at least approximately 0.6. 
     
     
         21 . An automobile drive train, comprising:
 an engine and transmission configured to deliver torque to a driveshaft;   a rear differential mounted on a suspension configured to receive torque from the driveshaft, the suspension permitting movement of the rear differential relative to the engine and transmission;   wherein said driveshaft comprises a slip yoke assembly having;
 an outer sleeve having an internal spline; 
 a yoke shaft slidably disposed within said outer sleeve, said yoke shaft having an external spline configured to engage said internal spline to form a splined joint; and 
 at least one bearing surface disposed between the outer sleeve and yoke shaft and spaced from the splined joint, said bearing surface configured and dimensioned to resist angular misalignment between said splined sleeve and said yoke shaft. 
   
     
     
         22 . An automobile drive train according to  claim 21 , further comprising a plurality of universal joints for coupling said driveshaft to said transmission and said rear differential. 
     
     
         23 . An automobile drive train according to  claim 21 , wherein said yoke shaft has an outer diameter, and wherein said bearing surface has a first axial contact length when said yoke shaft is fully extended at a design-maximum-extended position, and wherein a ratio of said first axial contact length to said outer diameter is in a range of about 0.6 to about 2. 
     
     
         24 . An automobile drive train according to  claim 21 , said yoke shaft assembly further comprising a rod wiper, and wherein said splined sleeve includes a rod wiper groove configured to house the rod wiper to thereby prevent contaminants from entering said slip yoke assembly.